In a conventional vacuum tube having a stationary and an axially movable contact, and a housing surrounding the contact region, a getter apparatus is usually arranged inside the housing. This getter apparatus serves to absorb gases which are produced during operation of the vacuum tube, and may degrade the quality of the vacuum. Conventional getter apparatuses have a support made of a sheet-metal strip on which the getter material, such as zirconium-aluminum or zirconium-titanium, is applied, and which is attached to a metal structural part of the vacuum tube, for example to the main screen or to an end flange. Usually, one or more getter fields are arranged on a strip-shaped substrate made of nickel, and this substrate is attached to a screen or an end flange of the vacuum tube by spot welding.
As described in, for example, German Patent Nos. DE 23 50 489 A1 and DE 29 48 310 A1, a heatable getter apparatus may also be configured in an annular fashion. The getter apparatus may be arranged concentrically with respect to the stationary contact pin of the vacuum tube.